Fuel tank tubing, bends.

I have had a hard time getting some tubing bent without kinking, even using a bending tube, the wound wire type and even after heating the tubing red hot to anneal it. Then I remembered an old trick and it works. I want to pass this on to those just starting or those my age that just forgot. After heating the tube red hot in a flame, and it is cool, put tape on one end and fill the open end with fine sand. I used the fine sand in my sand blaster. You don't have to have a sand blaster, but a half pint of the sand, the real fine stuff, is only a few bucks and most hobby shops can order it or buy it from Micro Mark or such. By filling the tube it will not collapse as it is bent and sharper bends can be made. Now I can install the darn tank and get this thing in the air. Ty M.

You can get the sand cheap at any ceramics shop. Buy what you need.

If you get the soft brass tubing, it should bend nicely all by itself. If you don't like brass (the soft brass has worked fine for us) the copper tubing will normally bend all by itself as well. But if the sand trick helps, go for it.

Just heating the tubing red hot and letting it cool slowly will not anneal brass. You need to heat and quench it in cool water immediately. This will render it dead soft and you can bend away, This is the standard (OLD!) method used to anneal rifle and pistol cartridge case necks so that they don't crack from working when being loaded/reloaded or in storage, which can happen if the brass is too hard.

Harry Higley sells a tubing bender that looks like a Hex nut. you can make 90 degree bends in hard tubing with it without collapsing the tubing. I'll have to try the sand trick. I wonder if microballoons would work.

>Harry Higley sells a tubing bender
>that looks like a Hex
>nut. you can make
>90 degree bends in hard
>tubing with it without collapsing
>the tubing.

I really like the Harry Higley bender. Using annealed copper and a bit of touch, you can make perfect tight bends.

What I neglected to say was the tubing was copper, used to extend the overflow tube and the uniflow tube, and it is the standard tubing we buy from our favorite U/C dealer. I always thought that heating the tubing would anneal it and by quenching it the temper was returned. Also, by working the copper after it is annealed, it will work hard again. Strange metal. The sand I used is aluminum silcate, very fine stuff I use to blast the surface of my brass locomotives prior to painting them.

LAST EDITED ON May-21-01 AT 07:41 AM (EST)

Quenching will harden ferrous metals, soften non-ferrous ones. See Donnelly's "The Handloaders Manual of Cartridge Conversions" pp 51-52 for reference on annealing brass.
You're right copper and brass is strange stuff.

Inserting .085" weed trimmer line in the tubing before using the Higley/Biso bender helps.

push a spring inside the tube and then bend it, no need to heat it at all.It will not kink enough to hinder fuel flow.
Pull the spring out, you will probably have to then throw it away as it will extend when you pull it ( rude joke... fellers, don't pull it too much....)
More seriously, if it is a stainless steel spring ( a lot of them are ) just leave it in the tube.

I put the wrong end of a drill bit in the tube and pull it out little by little as I bend the tube. Works pretty well. Seems like I read this in a helpful hints part a model magazine within the past year, because that is about how long I've been doing it with good results.

I use a tube bender that is American made, but there's nothing on it suggest who made it. It must be one of the big r/c firms though because I bought it in an Aussie model shop, and we don't stock anything made by the small specialists.

It's a flat metal handle, with a stud and a wheel mounted on one side - the edge of the wheel is recessed to allow the tube to sit in it. Basically, you hook the tube behind the stud and pull it around the wheel. It works a treat and gives a perfect bend every time - hard brass, soft brass, annealed brass, copper. About the only draw back is the distance from the stud to the wheel means that you can't make a bend any closer than 1/2" from the end of the tube.

But what the heck. A tank don't look home made unless the bends are all mangled.

Harry Higley makes some cute looking little tubing benders, too. Has anyone tried them? I find that if I use annealed brass (am changing to copper) and work it slowly and easily, a little bit at a time, I can do pretty nice bends freehand. Study the tank layout ahead of time and design the tubes for gentle bends.